A natural shortcoming of electronic devices that use batteries as a power source is battery capacity limitations. Unexpected power loss can cause data loss and other unexpected malfunctions. To avoid this, some electronic devices provide battery status indications (e.g. full battery status, empty battery status, or the level of available battery capacity in use) to inform users of battery status so that the users can take some action, such as saving data, before the battery depletes its energy and shuts down the system. Normally, one or more LEDs are used as an indicator to inform customers of the battery status.
It should be noted that the battery status herein refers to battery status, battery charging status or battery state of charge. In one embodiment, the battery capacity status is representative of a remaining battery capacity level.
There are some conventional methods or devices for indicating the battery status of an electronic device. U.S. Pat. No. 6,459,242 provides a pulse number method for indicating battery charge status by relating the number of pulses that occur in a predetermined time period with a certain battery status. By counting the blinking times in the predetermined time period, customers are able to know the corresponding battery status. U.S. Pat. Nos. 5,629,605 and 5,099,210 disclose a duty cycle method to indicate the charge status. In this approach, the amount of ON time exhibited by an LED over a predetermined period corresponds to battery status. However, a drawback of these methods is that the brightness of the indicator changes sharply due to the sudden change between ON and OFF states of the LED, which can cause visual discomfort to users. Another problem is that an extended period of time is needed to read the pulse number or sense the amount of ON time of the LED over a certain period.
U.S. Pat. No. 6,956,478 introduces a method using multiple LEDs with different colors. These different colors represent different charging states. The problem with this method is that some users are color-blind and are not able to distinguish between different colors. In addition, using multiple LEDs can increase cost.
Multiple LED scale methodologies are also commonly used in indicating battery status. In such approaches, the number of LEDs in an ON state represents a corresponding battery status. The multiple LEDs may be coupled to a controller either in parallel or in series. U.S. Pat. No. 6,950,030 discloses a multiple LED scale method that uses a series LED connection. However, in addition to multiple LEDs, a special high-voltage drive device and a high-voltage power source are also required. Multiple LED scale methods with independent LED control can also be found in conventional systems. The multiple LEDs are coupled in parallel to a controller and drive device. However, in addition to multiple LEDs, associated multiple pins for LED control are required, which is not cost effective.
Therefore, it is to a convenient, reliable, and cost effective battery status indication method or device that the present invention is primarily directed.